Active energy ray-curable resin composition, adhesive composition, and adhesive

Abstract

To provide an active energy ray-curable resin composition that has low viscosity; and has adhesion to various members, and good stickiness especially as an adhesive.SOLUTION: An active energy ray-curable resin composition contains a monofunctional urethane methacrylate compound (A) and a monofunctional ethylenic unsaturated monomer (B). The monofunctional ethylenic unsaturated monomer (B) contains a monofunctional ethylenic unsaturated monomer (B1) having a glass transition temperature of 0°C or higher and 130°C or lower as a homopolymer and a monofunctional ethylenic unsaturated monomer (B2) having a glass transition temperature of -60°C or higher and lower than 0°C as a homopolymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable resin composition, and more specifically to an active energy ray-curable resin composition that has low viscosity and good adhesion to various members, particularly good adhesive strength when used as a pressure-sensitive adhesive, and a pressure-sensitive adhesive composition and a pressure-sensitive adhesive using the same. [Background technology]

[0002] Conventionally, urethane (meth)acrylate compounds obtained by reacting a polyol compound, a polyisocyanate compound, and a hydroxyl group-containing (meth)acrylate compound have been known as components of active energy ray-curable resin compositions, and have been used in applications such as paints, coating agents, adhesives, and pressure-sensitive adhesives.

[0003] In particular, in recent years, pressure-sensitive adhesives have been used to bond optical devices such as touch panels and optical members such as optical recording media, and active energy ray-curable pressure-sensitive adhesives have been developed as such pressure-sensitive adhesives. For example, Patent Document 1 proposes an optical pressure-sensitive adhesive composition containing a monofunctional urethane (meth)acrylate oligomer, isobornyl (meth)acrylate, and a monofunctional diluent monomer having an ethylenically unsaturated group and a predetermined glass transition temperature in a predetermined content ratio. Furthermore, Patent Document 2 proposes an active energy ray-curable pressure-sensitive adhesive composition containing a urethane (meth)acrylate compound, a heterocycle-containing monomer, and a hydroxyl group-containing monomer in a predetermined content ratio. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-224841 [Patent Document 2] International Publication No. 2016 / 013510 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 uses two ethylenically unsaturated monomers, namely, isobornyl acrylate having a high glass transition temperature and a monomer having a glass transition temperature of 1°C or higher. This is insufficient in terms of adhesive strength, and the high viscosity makes it difficult to handle and results in poor coating. For this reason, it is still not yet satisfactory in terms of achieving both adhesive strength and low viscosity, and further improvement is required.

[0006] Furthermore, the technology disclosed in Patent Document 2 contains a bifunctional urethane (meth)acrylate compound having two ethylenically unsaturated groups in one molecule and two types of ethylenically unsaturated monomers. However, since the urethane (meth)acrylate compound is bifunctional, there are concerns that the viscosity may not be sufficiently reduced, and further improvements are required from the viewpoints of low viscosity and adhesive strength.

[0007] Under these circumstances, an object of the present invention is to provide an active energy ray-curable resin composition that has low viscosity and good adhesion to various members, particularly good adhesive strength when used as a pressure-sensitive adhesive, and to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive comprising the same. [Means for solving the problem]

[0008] However, as a result of intensive research by the present inventors to solve the above-mentioned problems, they found that in an active energy ray-curable resin composition containing a urethane (meth)acrylate compound and an ethylenically unsaturated monomer, by using a monofunctional urethane (meth)acrylate compound having one ethylenically unsaturated group per molecule as the urethane (meth)acrylate compound and using two types of monofunctional ethylenically unsaturated monomers having one ethylenically unsaturated group per molecule as the ethylenically unsaturated monomer, one having a higher glass transition temperature when made into a homopolymer and the other having a lower glass transition temperature, the composition has low viscosity and exhibits good adhesion to various members, particularly good adhesive strength when made into a pressure-sensitive adhesive, and thus completed the present invention.

[0009] That is, the present invention has the following aspects [1] to

[12] . [1] An active energy ray-curable resin composition comprising a monofunctional urethane (meth)acrylate compound (A) and a monofunctional ethylenically unsaturated monomer (B), wherein the monofunctional ethylenically unsaturated monomer (B) contains a monofunctional ethylenically unsaturated monomer (B1) having a glass transition temperature of 0°C or higher and 130°C or lower when made into a homopolymer, and a monofunctional ethylenically unsaturated monomer (B2) having a glass transition temperature of -60°C or higher and lower than 0°C when made into a homopolymer. [2] The active energy ray-curable resin composition according to [1], wherein the monofunctional urethane (meth)acrylate compound (A) is a reaction product of a polyol (a1), a polyisocyanate (a2), a hydroxyl group-containing (meth)acrylate (a3), and a monool (a4). [3] The active energy ray-curable resin composition according to [2], wherein the polyol (a1) is a plant-derived polyol. [4] The active energy ray-curable resin composition according to [2] or [3], wherein the monool (a4) is a monool having 3 or more carbon atoms. [5] The active energy ray-curable resin composition according to any one of [1] to [4], wherein the monofunctional urethane (meth)acrylate compound (A) is a monofunctional urethane (meth)acrylate compound in which an isocyanate group in a compound (X) having isocyanate groups at both ends, which is a reaction product of a polyol (a1) and a polyisocyanate (a2), and a hydroxyl group in a hydroxyl group-containing (meth)acrylate (a3) ​​and a monool (a4), respectively, form a urethane bond. [6] The active energy ray-curable resin composition according to any one of [1] to [5], wherein the monofunctional urethane (meth)acrylate compound (A) has a weight average molecular weight of 5,000 to 100,000. [7] The active energy ray-curable resin composition according to any one of [1] to [6], wherein the content of the monofunctional ethylenically unsaturated monomer (B) is 20 to 150 parts by weight per 100 parts by weight of the monofunctional urethane (meth)acrylate compound (A). [8] The active energy ray-curable resin composition according to any one of [1] to [7], wherein the content ratio (B1 / B2) of the monofunctional ethylenically unsaturated monomer (B1) that, when made into a homopolymer, gives a glass transition temperature of 0°C or more and 130°C or less, and the content ratio of the monofunctional ethylenically unsaturated monomer (B2) that, when made into a homopolymer, gives a glass transition temperature of -60°C or more and less than 0°C, is 70 / 30 to 30 / 70 (weight ratio). [9] The active energy ray-curable resin composition according to any one of [1] to [8], wherein the composition comprising the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated monomer (B) has a bio-content of 50 C% or more.

[10] The active energy ray-curable resin composition according to any one of [1] to [9], further comprising a photopolymerization initiator (C).

[11] A pressure-sensitive adhesive composition comprising the active energy ray-curable resin composition according to any one of [1] to

[10] .

[12] A pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to

[11] .

[0010] Generally, polyfunctional urethane (meth)acrylate compounds obtained by reacting polyols, polyisocyanates, and hydroxyl group-containing (meth)acrylates have high viscosities and are difficult to handle due to their multifunctionality and large molecular weight. However, polyfunctional urethane (meth)acrylate compounds have excellent photocurability due to their multifunctionality, and are therefore used in adhesives, coating agents, etc. Therefore, it is common practice to avoid using monofunctional urethane (meth)acrylate compounds as active energy ray-curable resin compositions from the viewpoint of photocurability. However, the present invention aims to reduce viscosity, and surprisingly, it has been found that low viscosity can be achieved even when using monofunctional urethane (meth)acrylate compounds without reducing photocurability. Furthermore, it has been found that when using monofunctional urethane (meth)acrylate compounds, a monofunctional monomer with a high glass transition temperature and a monofunctional monomer with a low glass transition temperature can be used in combination to obtain an active energy ray-curable resin composition that has low viscosity but excellent adhesive strength. [Effects of the Invention]

[0011] The active energy ray-curable resin composition of the present invention has low viscosity and excellent adhesion to various members, and is an active energy ray-curable resin composition that can be used in various applications such as coating agents, paints, inks, pressure-sensitive adhesives, etc. In particular, the active energy ray-curable resin composition of the present invention has good adhesive strength when used as a pressure-sensitive adhesive, and is therefore useful as a pressure-sensitive adhesive. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited to these.

[0013] In the present invention, "(meth)acrylic" means "acrylic" or "methacrylic", and "(meth)acrylate" means "acrylate" or "methacrylate", respectively. In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also derivatives of carboxylic acids such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters. In the present invention, the term "sheet" is not particularly distinguished from "film" or "tape" and is used to include these terms.

[0014] The active energy ray-curable resin composition of the present invention contains a monofunctional urethane (meth)acrylate compound (A) and a monofunctional ethylenically unsaturated monomer (B). Each component will be described in detail below.

[0015] [Monofunctional urethane (meth)acrylate compound (A)] The monofunctional urethane (meth)acrylate compound (A) has one (meth)acryloyl group in its molecule. Among them, the monofunctional urethane (meth)acrylate compound (A) is preferably a reaction product of a polyol (a1), a polyisocyanate (a2), a hydroxyl group-containing (meth)acrylate (a3), and a monool (a4) from the viewpoint of low viscosity.

[0016] [Polyol (a1)] The polyol (a1) is preferably a plant-derived polyol, since it can have a high bio-content, which indicates the proportion of plant-derived carbon in the total carbon contained in the composition, etc. The higher the bio-content, the lower the environmental impact.

[0017] Examples of the polyol (a1) include polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, and polysiloxane polyols. These may be used alone or in combination of two or more. Of these, polyester polyols are preferred.

[0018] Examples of the polyester polyol include a condensation polymer of a polyhydric alcohol and a polycarboxylic acid, a ring-opening polymer of a cyclic ester (lactone), and a reaction product of three components: a polyhydric alcohol, a polycarboxylic acid, and a cyclic ester. Among these, a condensation polymer of a polyhydric alcohol and a polycarboxylic acid is preferred, a polycondensation polymer of a polyhydric alcohol and a dimer acid, or a polycondensation polymer of a dimer diol obtained by reducing a dimer acid and a polycarboxylic acid is more preferred, and a polycondensation polymer of a polyhydric alcohol and a dimer acid is particularly preferred.

[0019] The dimer acids are unsaturated fatty acids derived from vegetable oils and fats, and the use of dimer acids can increase the bio content of the monofunctional urethane (meth)acrylate compound (A). Examples of the dimer acids include thermal dimers of unsaturated fatty acids and hydrogenated dimer acids obtained by hydrogenating these.

[0020] Examples of polyhydric alcohols to be polycondensed with dimer acids include aliphatic or alicyclic polyhydric alcohols having 2 to 40 carbon atoms, such as linear polyhydric alcohols having 2 to 20 carbon atoms, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, and 1,20-eicosanediol; Examples of the polyhydric alcohols include polyhydric alcohols having a branched chain of 4 to 40 carbon atoms, such as 1,3-butanediol, 2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2-ethyl-1,6-hexanediol, 2,4-diethyl-1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and dimer diol; polyhydric alcohols having a cyclic structure in the molecule of 4 to 20 carbon atoms, such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; diethylene glycol, triethylene glycol, polytetramethylene ether glycol, and dimer diol. These polyhydric alcohols may be used alone or in combination of two or more. Among these, in terms of availability and adhesive strength when used as an adhesive, linear polyhydric alcohols having 2 to 10 carbon atoms and branched polyhydric alcohols having 4 to 10 carbon atoms are preferred, and 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol are particularly preferred.

[0021] That is, the polycondensation product of the polyhydric alcohol and the dimer acid is particularly preferably a polycondensation product of the dimer acid and at least one glycol selected from 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol, and is particularly preferably a polycondensation product of the dimer acid and 1,4-butanediol.

[0022] Examples of the polycarboxylic acid of the polycarboxylic acids that undergo polycondensation reaction with the dimer diol include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, trimellitic acid, and furandicarboxylic acid. Among these, aliphatic dicarboxylic acids are preferred in terms of availability and adhesive strength when used as an adhesive, and succinic acid, adipic acid, and sebacic acid are particularly preferred.

[0023] In terms of ease of handling and adhesive strength when used as a pressure-sensitive adhesive, the number-average molecular weight of the polyester polyol is preferably 800 to 5000, particularly 1000 to 4000, and even more preferably 2000 to 3000. If the number-average molecular weight is too small, the adhesive strength when used as a pressure-sensitive adhesive tends to be low, whereas if the number-average molecular weight is too large, the viscosity tends to be high, and the handleability and reactivity tend to be reduced.

[0024] The number average molecular weight can be determined by measuring the hydroxyl value of the polyester polyol using an acetylating reagent or a phthalating reagent in accordance with JIS K1557-1 (2007).

[0025] Examples of the polyether polyol include alkylene structure-containing polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, and polyhexamethylene glycol, and random or block copolymers of these polyalkylene glycols.

[0026] Examples of the polycarbonate polyol include a reaction product of a polyhydric alcohol with phosgene, and a ring-opening polymer of a cyclic carbonate (such as alkylene carbonate).

[0027] Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polyester polyol, and examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0028] The polycarbonate polyol may be any compound having a carbonate bond in the molecule and a hydroxyl group at the end, and may have an ester bond in addition to the carbonate bond.

[0029] The polyolefin polyols include those having a saturated hydrocarbon skeleton of a homopolymer or copolymer of ethylene, propylene, butene, or the like, and having a hydroxyl group at the molecular end, such as polyisoprene polyols, polybutadiene polyols, nitrile butadiene polyols, and styrene butadiene polyols. The polyolefin polyol may be a hydrogenated polyolefin polyol in which all or part of the ethylenically unsaturated groups contained in the structure thereof have been hydrogenated.

[0030] Examples of the polysiloxane polyol include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

[0031] [Polyisocyanate (a2)] Examples of the polyisocyanate (a2) used in the present invention include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate; and aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, as well as trimer compounds of the above polyisocyanates and polymeric compounds of the above polyisocyanates. Other examples include allophanate-type polyisocyanates, biuret-type polyisocyanates, etc. These may be used alone or in combination of two or more.

[0032] Among these, in terms of adhesive properties when used as an adhesive, aliphatic polyisocyanates and alicyclic polyisocyanates are preferred, and isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, and hexamethylene diisocyanate are more preferred, with isophorone diisocyanate being particularly preferred.

[0033] [Hydroxyl group-containing (meth)acrylate (a3)] Examples of the hydroxyl group-containing (meth)acrylate (a3) ​​used in the present invention include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, as well as hydroxyl group-containing (meth)acrylates containing one ethylenically unsaturated group, such as 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol mono(meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate. These may be used alone or in combination of two or more.

[0034] Among these, hydroxyalkyl (meth)acrylates are preferred, particularly in terms of adhesive properties when used as adhesives, more preferably hydroxyalkyl (meth)acrylates in which the alkyl group has 1 to 4 carbon atoms, and particularly preferably 4-hydroxybutyl acrylate.

[0035] [Monoall (a4)] The monool (a4) used in the present invention is preferably a monool having 3 or more carbon atoms, more preferably a monool having 3 to 30 carbon atoms, and particularly preferably a monool having 3 to 20 carbon atoms, in terms of low viscosity.

[0036] Examples of the monool (a4) include linear aliphatic monools such as propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, lauryl alcohol, myristyl alcohol (tetradecanol), pentadecanol, cetyl alcohol (hexadecanol), heptadecanol, stearyl alcohol (octadecanol), and nonadecanol; aliphatic monools such as branched aliphatic monools such as isopropanol, isobutanol, t-butanol, and isohexadecanol; alicyclic monools such as cyclohexanol and methylcyclohexanol; and aromatic monools such as benzyl alcohol. These may be used alone or in combination of two or more. Among these, aliphatic monools are preferred, and propanol and isohexadecanol are particularly preferred.

[0037] The monofunctional urethane (meth)acrylate compound (A) used in the present invention can be obtained by reacting the above components (a1) to (a4). The production method thereof may be a known method, for example, (i) A method in which the polyol (a1), the polyisocyanate (a2), the hydroxyl group-containing (meth)acrylate (a3), and the monool (a4) are charged into a reactor all at once or separately and reacted; (ii) a method of reacting an isocyanate group in a compound (X) having isocyanate groups at both ends, which is a reaction product of a polyol (a1) and a polyisocyanate (a2), with a hydroxyl group contained in a hydroxyl group-containing (meth)acrylate (a3) ​​and a monool (a4); (iii) A method of reacting a terminal isocyanate-containing compound (Y) which is a reaction product of a polyisocyanate (a2) and a hydroxyl group-containing (meth)acrylate (a3), a terminal isocyanate-containing compound (Z) which is a reaction product of a polyisocyanate (a2) and a monool (a4), and a compound (W) which contains hydroxyl groups at both ends which is a reaction product of a polyol (a1) or a polyol (a1) and a polyisocyanate (a2), However, method (ii) is preferred in terms of reaction stability and reduction of by-products.

[0038] In the above method (ii), the reaction between the polyol (a1) and the polyvalent isocyanate (a2) can be carried out by a known reaction means. In this case, for example, the molar ratio of the isocyanate groups in the polyvalent isocyanate (a2) to the hydroxyl groups in the polyol (a1) is usually about 2n:(2n-2) (n is an integer of 2 or more), thereby obtaining the compound (X) containing isocyanate groups at both ends.

[0039] In the above molar ratio, n is 4 or more and 10 or less. The lower limit is preferably 5 or more, more preferably 6 or more. The upper limit is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less. If n is too small, the adhesive strength when used as a pressure-sensitive adhesive tends to be low, and if n is too large, the viscosity of the active energy ray-curable resin composition tends to increase, making it difficult to handle.

[0040] The reaction molar ratio of the compound (X) containing isocyanate groups at both ends, which is a reaction product of the polyol (a1) and the polyisocyanate (a2), to the hydroxyl group-containing (meth)acrylate (a3) ​​is usually about 1:1 (compound (X) containing isocyanate groups at both ends):hydroxyl group-containing (meth)acrylate (a3) ​​when the compound (X) containing isocyanate groups at both ends has two isocyanate groups and the hydroxyl group-containing (meth)acrylate (a3) ​​has one hydroxyl group; and the reaction molar ratio of the compound (X) containing isocyanate groups at both ends:hydroxyl group-containing (meth)acrylate (a3) ​​is usually about 1:1.5 (compound (X) containing isocyanate groups at both ends):hydroxyl group-containing (meth)acrylate (a3) ​​when the compound (X) containing isocyanate groups at both ends has three isocyanate groups and the hydroxyl group-containing (meth)acrylate (a3) ​​has one hydroxyl group.

[0041] The reaction molar ratio between the compound (X) containing isocyanate groups at both ends and the monol (a4) is usually about 1:1 (compound (X) containing isocyanate groups at both ends):monol (a4) when the compound (X) containing isocyanate groups at both ends has two isocyanate groups, and usually about 1:1.5 (compound (X) containing isocyanate groups at both ends):monool (a4) when the compound (X) containing isocyanate groups at both ends has three isocyanate groups.

[0042] Furthermore, when the compound (X) containing isocyanate groups at both ends is reacted with the hydroxyl group-containing (meth)acrylate (a3) ​​and the monol (a4), the molar ratio of the hydroxyl group-containing (meth)acrylate (a3) ​​to the monol (a4) is usually about 1:1 (hydroxyl group-containing (meth)acrylate (a3):monol (a4), for example, when the hydroxyl group-containing (meth)acrylate (a3) ​​has one hydroxyl group.

[0043] In the reaction between the polyol (a1) and the polyisocyanate (a2), and further in the reaction between the compound (X) containing isocyanate groups at both ends and the hydroxyl group-containing (meth)acrylate (a3) ​​and the monool (a4), it is also preferable to use a catalyst to promote the reaction.

[0044] Examples of such catalysts include organometallic compounds such as dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octoate, tin octoate, cobalt naphthenate, stannous chloride, and stannic chloride; amine catalysts such as triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, and N-ethylmorpholine; bismuth nitrate, bismuth bromide, and bismuth iodide; Examples of suitable bismuth catalysts include bismuth, bismuth sulfide, and organic bismuth compounds such as dibutyl bismuth dilaurate and dioctyl bismuth dilaurate, and organic acid bismuth salts such as bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth bisneodecanoate, bismuth disalicylate, and bismuth digallate. Among these, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferred.

[0045] In the reaction between the polyol (a1) and the polyisocyanate (a2), and further in the reaction between the compound (X) containing isocyanate groups at both ends and the hydroxyl group-containing (meth)acrylate (a3) ​​and the monool (a4), organic solvents that do not have a functional group that reacts with an isocyanate group, such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene, can be used.

[0046] The reaction temperature is usually 30 to 90°C, preferably 40 to 80°C, and the reaction time is usually 2 to 12 hours, preferably 3 to 10 hours.

[0047] In the addition reaction of the compound (X) containing isocyanate groups at both ends with the hydroxyl group-containing (meth)acrylate (a3) ​​and the monool (a4), the reaction is terminated when the content of residual isocyanate groups in the reaction system generally reaches 0.3% by weight or less, thereby obtaining a monofunctional urethane (meth)acrylate compound (A).

[0048] The weight-average molecular weight of the monofunctional urethane (meth)acrylate compound (A) is preferably 5,000 to 100,000, particularly preferably 7,000 to 90,000, further preferably 8,000 to 70,000, and particularly preferably 10,000 to 30,000. If the weight-average molecular weight is too small, the adhesive strength when used as a pressure-sensitive adhesive tends to be low, whereas if it is too large, the viscosity of the resin composition increases, making it difficult to handle, and it tends to gel due to impurities.

[0049] The number average molecular weight of the monofunctional urethane (meth)acrylate compound (A) is preferably 3000 to 30000, particularly preferably 4000 to 25000, further preferably 5000 to 20000, and particularly preferably 7000 to 15000. If the number average molecular weight is too small, the adhesive strength when used as a pressure-sensitive adhesive tends to be low, whereas if it is too large, the viscosity of the resin composition increases, making it difficult to handle, and it tends to gel due to impurities.

[0050] Furthermore, the dispersity (weight average molecular weight / number average molecular weight) of the monofunctional urethane (meth)acrylic compound (A) is preferably 20 or less, particularly preferably 10 or less, even more preferably 7 or less, and especially preferably 5 or less. If the dispersity is too high, gelation tends to occur. The lower limit of the dispersity is usually 1.1 in view of production limitations.

[0051] The weight-average molecular weight and number-average molecular weight are measured in terms of standard polystyrene molecular weight using a high-performance liquid chromatograph (Waters, "ACQUITY APC System") equipped with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45. If the sample contains a monofunctional ethylenically unsaturated monomer (B), the number-average molecular weight and weight-average molecular weight are determined excluding the monofunctional ethylenically unsaturated monomer (B).

[0052] [Monofunctional ethylenically unsaturated monomer (B)] The monofunctional ethylenically unsaturated monomer (B) used in the present invention contains a monofunctional ethylenically unsaturated monomer (B1) (hereinafter referred to as "ethylenically unsaturated monomer (B1)") that has a glass transition temperature of 0°C or higher and 130°C or lower when made into a homopolymer, and a monofunctional ethylenically unsaturated monomer (B2) (hereinafter referred to as "ethylenically unsaturated monomer (B2)") that has a glass transition temperature of -60°C or higher and lower than 0°C when made into a homopolymer. That is, in the present invention, by using in combination an ethylenically unsaturated monomer (B1) having a high glass transition temperature within a predetermined range and an ethylenically unsaturated monomer (B2) having a low glass transition temperature within a predetermined range, it is possible to obtain a composition having low viscosity and excellent adhesion to various members.

[0053] In the present invention, the glass transition temperature of a homopolymer of the monofunctional ethylenically unsaturated monomer (B) can be the value described in POLYM HANDBOOK Fourth Edition, John Wiley & Sons, Inc. (1999) or "Polymer Data Handbook" edited by the Society of Polymer Science (1986). For the glass transition temperature (Tg) of a homopolymer not described therein, the value described in other literature or product catalogs or the value measured by producing a homopolymer can be used.

[0054] The content of the monofunctional ethylenically unsaturated monomer (B) is preferably 20 to 150 parts by weight, more preferably 50 to 120 parts by weight, and particularly preferably 70 to 100 parts by weight, relative to 100 parts by weight of the monofunctional urethane (meth)acrylate compound (A). When the content of the monofunctional ethylenically unsaturated monomer (B) is within the above range, the viscosity tends to be low and the adhesion to various members tends to be excellent.

[0055] [Ethylenically unsaturated monomer (B1)] The ethylenically unsaturated monomer (B1) has a glass transition temperature of 0° C. or higher and 130° C. or lower, preferably 10° C. or higher and 120° C. or lower, and more preferably 20° C. or higher and 100° C. or lower when made into a homopolymer. If the lower limit of the glass transition temperature of the ethylenically unsaturated monomer (B1) is below the above-mentioned numerical value, the viscosity tends to be high, and if the upper limit of the glass transition temperature exceeds the above-mentioned numerical value, the adhesive strength tends to be reduced.

[0056] Examples of the ethylenically unsaturated monomer (B1) include styrene-based monomers such as styrene (100°C); alkyl (meth)acrylates such as methyl (meth)acrylate (Tga 8°C, Tgm 105°C), ethyl methacrylate (Tgm 65°C), n-butyl methacrylate (Tgm 20°C), isobutyl methacrylate (Tgm 48°C), t-butyl (meth)acrylate (Tga 41°C, Tgm 107°C), and n-stearyl (meth)acrylate (Tga 30°C, Tgm 38°C); hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl methacrylate (Tgm 55°C) and 2-hydroxypropyl methacrylate (Tgm 26°C); amino group-containing (meth)acrylates such as dimethylaminoethyl methacrylate (Tgm 18°C) and diethylaminoethyl methacrylate (Tgm 16 to 24°C); Examples of suitable (meth)acrylate monomers include alicyclic (meth)acrylates such as cyclohexyl acrylate (Tga 97°C), cyclohexyl (meth)acrylate (Tga 15°C, Tgm 66°C), and 3,3,5-trimethylcyclohexyl acrylate (Tga 52°C); aromatic (meth)acrylates such as benzyl (meth)acrylate (Tga 6°C, Tgm 54°C); and heterocyclic (meth)acrylates such as tetrahydrofurfuryl methacrylate (Tgm 60°C), glycidyl (meth)acrylate (Tga 60°C, Tgm 46°C), (3-ethyloxetan-3-yl)methyl methacrylate (Tgm 2°C), and cyclic trimethylolpropane formal acrylate (Tga 27°C); vinyl acetate (29°C); and amide monomers such as hydroxyethyl acrylamide (98°C) and diethyl acrylamide (81°C). These may be used alone or in combination of two or more. Among them, alicyclic (meth)acrylates and heterocyclic (meth)acrylates are preferred, and isobornyl acrylate and cyclic trimethylolpropane formal acrylate are particularly preferred. The numbers in parentheses indicate glass transition temperatures. "Tga" indicates acrylates, and "Tgm" indicates methacrylates.

[0057] The content of the ethylenically unsaturated monomer (B1) is preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight, and particularly preferably 30 to 60 parts by weight, relative to 100 parts by weight of the monofunctional urethane (meth)acrylate compound (A). When the content of the ethylenically unsaturated monomer (B1) is within the above range, a low viscosity tends to be achieved.

[0058] [Ethylenically unsaturated monomer (B2)] The ethylenically unsaturated monomer (B2) has a glass transition temperature, when made into a homopolymer, of −60° C. or higher and lower than 0° C., preferably −50° C. or higher and −5° C. or lower, and more preferably −30° C. or higher and −10° C. If the lower limit of the glass transition temperature of the ethylenically unsaturated monomer (B2) is lower than the above-mentioned numerical value, the viscosity tends to be high, and if the upper limit of the glass transition temperature is equal to or higher than the above-mentioned numerical value, the adhesive strength tends to be low.

[0059] Examples of the ethylenically unsaturated monomer (B2) include alkyl (meth)acrylates such as n-butyl acrylate (Tga -56°C), isobutyl acrylate (Tga -26°C), 2-ethylhexyl methacrylate (Tgm -10°C), isononyl acrylate (Tga -58°C), n-lauryl acrylate (Tga -23°C), nonyl acrylate (Tga -37°C), isostearyl acrylate (Tga -18°C), and isodecyl methacrylate (Tgm -41°C); 2-hydroxyethyl acrylate (Tga -15°C), 2-hydroxypropyl acrylate (Tga -7°C), and 4-hydroxybutyl acrylate (Tga Examples of (meth)acrylate monomers include hydroxyl group-containing (meth)acrylates such as (Tga -32°C), aromatic (meth)acrylates such as phenoxyethyl acrylate (Tga -22°C), heterocyclic (meth)acrylates such as tetrahydrofurfuryl acrylate (Tga -12°C), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (Tga -7°C), and 4-hydroxybutyl acrylate glycidyl ether (Tga -59°C), and alkoxy group-containing (meth)acrylates such as 2-methoxyethyl (meth)acrylate (Tga -50°C, Tgm -2°C) and 2-ethoxyethyl methacrylate (Tgm -31°C). These may be used alone or in combination of two or more. Among these, alkyl (meth)acrylates, aromatic (meth)acrylates, and heterocyclic (meth)acrylates are preferred, with n-butyl acrylate, phenoxyethyl acrylate, and tetrahydrofurfuryl acrylate being more preferred, with phenoxyethyl acrylate and tetrahydrofurfuryl acrylate being particularly preferred, and tetrahydrofurfuryl acrylate being particularly preferred. The values ​​in parentheses indicate glass transition temperatures. Furthermore, "Tga" indicates acrylates, and "Tgm" indicates methacrylates.

[0060] The content of the ethylenically unsaturated monomer (B2) is preferably 10 to 100 parts by weight, more preferably 10 to 80 parts by weight, and particularly preferably 15 to 60 parts by weight, relative to 100 parts by weight of the monofunctional urethane (meth)acrylate compound (A). When the content of the ethylenically unsaturated monomer (B2) is within the above range, the adhesive strength tends to be excellent.

[0061] The weight ratio (B1 / B2) of the ethylenically unsaturated monomer (B1) to the ethylenically unsaturated monomer (B2) is preferably 70 / 30 to 30 / 70, more preferably 65 / 35 to 35 / 65, and particularly preferably 65 / 35 to 40 / 60. When the weight ratio of the ethylenically unsaturated monomer (B1) to the ethylenically unsaturated monomer (B2) is within the above range, the viscosity tends to be low and the adhesion to various members tends to be excellent.

[0062] The difference in glass transition temperature between the ethylenically unsaturated monomer (B1) and the ethylenically unsaturated monomer (B2) is usually 30 to 160° C., preferably 50 to 130° C., and more preferably 60 to 120° C. When the difference in glass transition temperature between the ethylenically unsaturated monomer (B1) and the ethylenically unsaturated monomer (B2) is within the above range, the composition tends to have low viscosity and excellent adhesion to various members.

[0063] Furthermore, the monofunctional ethylenically unsaturated monomer (B) may contain a monofunctional ethylenically unsaturated monomer (B3) other than the ethylenically unsaturated monomer (B1) and the ethylenically unsaturated monomer (B2) within a range that does not impair the effects of the present invention (for example, 10% by weight or less of the monofunctional ethylenically unsaturated monomer (B)). However, in the present invention, it is preferred that the monofunctional ethylenically unsaturated monomer (B) consists solely of the ethylenically unsaturated monomer (B1) and the ethylenically unsaturated monomer (B2).

[0064] Examples of the monofunctional ethylenically unsaturated monomer (B3) include 2-ethylhexyl acrylate (Tga -70°C), 4-hydroxybutyl acrylate (Tga -80°C), ethyl carbitol acrylate (Tga -67°C), ethoxydiethylene glycol acrylate (Tga -70°C), lauryl methacrylate (Tgm -65°C), octyl acrylate (Tga -65°C), isooctyl acrylate (Tga -70°C), tetradecyl methacrylate (Tgm -72°C), acryloylmorpholine (145°C), isopropylacrylamide (134°C), dimethylaminopropylacrylamide (134°C), 1-adamantyl methacrylate (Tgm 250°C), 1-adamantyl acrylate (Tga 153°C), acrylamide (153°C), etc. These may be used alone or in combination of two or more. The numbers in parentheses indicate the glass transition temperatures. Additionally, "Tga" indicates acrylate, and "Tgm" indicates methacrylate.

[0065] [Photopolymerization initiator (C)] The active energy ray-curable resin composition of the present invention preferably further contains a photopolymerization initiator (C) in order to more efficiently carry out curing with active energy rays.

[0066] Examples of the photopolymerization initiator (C) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)-phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy acetophenones such as 2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, and phenylglyoxylic acid methyl ester; Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo benzophenones such as (4-benzoylbenzyl)trimethylammonium chloride and (2-propenyloxy)ethyl]benzenemethanaminium bromide; thioxanthones such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride;Examples of suitable acylphosphine oxides include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. These may be used alone or in combination of two or more.

[0067] Among these, acetophenones and benzoins are preferred, more preferably benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin isopropyl ether, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl) ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one, and particularly preferably 1-hydroxycyclohexyl phenyl ketone.

[0068] Furthermore, as an auxiliary agent for the photopolymerization initiator (C), it is also possible to use in combination triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and the like.

[0069] The content of the photopolymerization initiator (C) is preferably 0.1 to 40 parts by weight, more preferably 0.5 to 20 parts by weight, and even more preferably 1 to 10 parts by weight, per 100 parts by weight of the total of the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated monomer (B) (including the polyfunctional ethylenically unsaturated monomer if one is used, as described below). If the content of the photopolymerization initiator (C) is too low, curing tends to be insufficient, while if it is too high, solution stability tends to decrease, such as precipitation when applied, and problems such as embrittlement and coloration tend to occur.

[0070] Furthermore, the active energy ray-curable resin composition of the present invention may further contain other components, such as a polyfunctional ethylenically unsaturated monomer, a surface conditioner, a leveling agent, a polymerization inhibitor, etc. These may be used alone or in combination of two or more.

[0071] The polyfunctional ethylenically unsaturated monomers include difunctional ethylenically unsaturated monomers and trifunctional or higher ethylenically unsaturated monomers, which may be used alone or in combination of two or more.

[0072] The bifunctional ethylenically unsaturated monomer may be any monomer containing two ethylenically unsaturated groups, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, and propylene oxide-modified bisphenol A di(meth)acrylate. acrylate, 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide-modified di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid-modified neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide-modified diacrylate, and 2-(meth)acryloyloxyethyl acid phosphate diester.

[0073] The tri- or higher functional ethylenically unsaturated monomer may be any monomer containing three or more ethylenically unsaturated groups, and examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanuric acid ethylene oxide modified triacrylate, and ethylene oxide modified dipentaerythritol. Examples of the acrylate include penta(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, and succinic acid-modified pentaerythritol tri(meth)acrylate.

[0074] The surface conditioner is not particularly limited, and examples thereof include alkyd resins. Such alkyd resins have the effect of imparting film-forming properties during coating and the effect of increasing adhesion to the surface of a thin metal film.

[0075] As the leveling agent, any known leveling agent can be used as long as it has the effect of imparting wettability to the substrate and reducing the surface tension of the coating liquid, such as silicone-modified resins, fluorine-modified resins, alkyl-modified resins, etc. These can be used alone or in combination of two or more kinds.

[0076] Examples of the polymerization inhibitor include p-benzoquinone, naphthoquinone, toluquinone, 2,5-diphenyl-p-benzoquinone, hydroquinone, 2,5-di-t-butylhydroquinone, methylhydroquinone, methoxyphenol, 2,6-di-t-butyl-p-cresol, mono-t-butylhydroquinone, and pt-butylcatechol. Among these, methoxyphenol and 2,6-di-t-butyl-p-cresol are preferred. These can be used alone or in combination of two or more.

[0077] The active energy ray-curable composition of the present invention can be obtained by mixing the monofunctional urethane (meth)acrylate compound (A), the monofunctional ethylenically unsaturated monomer (B), preferably the photopolymerization initiator (C), and other components as needed. The mixing method is not particularly limited, and various methods can be used for mixing. For example, the components can be mixed all at once, or any component can be mixed first, followed by the remaining components, and other methods can be appropriately selected. Thus, the active energy ray-curable resin composition of the present invention can be obtained.

[0078] <Active energy ray-curable resin composition> The viscosity of the active energy ray-curable resin composition of the present invention at 60°C is preferably less than 3500 mPa·s, more preferably less than 2500 mPa·s, and even more preferably less than 1500 mPa·s. If the viscosity is too high, the handling properties tend to be reduced. Here, the viscosity is measured using an E-type viscometer.

[0079] As described above, the active energy ray-curable resin composition of the present invention contains a monofunctional urethane (meth)acrylate compound (A) and a monofunctional ethylenically unsaturated monomer (B), and the composition consisting of the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated monomer (B) preferably has a bio-content of 50 C% or more ("C%" represents the proportion of carbon), more preferably 60 C% or more, and particularly preferably 70 C% or more. By making the bio-content of the composition consisting of the monofunctional urethane (meth)acrylate compound and the monofunctional ethylenically unsaturated monomer (B) equal to or greater than the above numerical value, an active energy ray-curable resin composition with reduced environmental impact can be obtained.

[0080] The bio-content represents the proportion of plant-derived carbon in the total carbon contained in the composition, and can be calculated by calculating the proportion of plant-derived carbon from all the carbon in the raw materials constituting the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated monomer (B). More precisely, it can be measured by the method specified in ASTM D6866.

[0081] The active energy ray-curable resin composition of the present invention can be suitably used as a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition is cured by irradiation with active energy rays and exhibits its function as a pressure-sensitive adhesive. Usually, the pressure-sensitive adhesive composition is applied to various substrates, dried, and then cured by irradiation with active energy rays.

[0082] The method for applying the pressure-sensitive adhesive composition is not particularly limited, and examples thereof include wet coating methods such as spraying, showering, dipping, rolling, spinning, curtain, flow, slitting, die, gravure, comma, dispenser, screen printing, and inkjet printing.

[0083] The coating may be carried out by blending an organic solvent, if necessary, to adjust the viscosity, and examples of such organic solvents include alcohols such as methanol, ethanol, propanol, n-butanol, and isobutanol, ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, cellosolves such as ethyl cellosolve, aromatic compounds such as toluene and xylene, glycol ethers such as propylene glycol monomethyl ether, acetates such as methyl acetate, ethyl acetate, and butyl acetate, diacetone alcohol, etc. These organic solvents may be used alone or in combination of two or more.

[0084] When the pressure-sensitive adhesive composition is a solid or a highly viscous liquid, a hot melt method may be used in which the pressure-sensitive adhesive composition is heated to reduce the viscosity and then coated by the above method.

[0085] Examples of the substrate include thermoplastic resins such as polyolefin resins, polyester resins, polycarbonate resins, acrylonitrile butadiene styrene copolymers (ABS), polystyrene resins, and polyamide resins; metal deposition layers, metals such as copper, stainless steel (SUS304, SUSBA, etc.), aluminum, zinc, and magnesium; glass; and composite substrates thereof.

[0086] The shape of the substrate is not particularly limited, and examples thereof include a sheet, a plate, a molded product made of the substrate, etc. When the substrate is a thermoplastic resin and has a sheet shape, a pressure-sensitive adhesive composition can be applied to the substrate, dried, and then irradiated with active energy rays to form a pressure-sensitive adhesive sheet.

[0087] Examples of such active energy rays that can be used include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays, electromagnetic waves such as X-rays and gamma rays, as well as electron beams, proton beams, and neutron beams, but curing with ultraviolet rays is advantageous in terms of curing speed, ease of availability of irradiation equipment, cost, etc. When curing is performed with electron beams, curing can be achieved without using a photopolymerization initiator (C).

[0088] For UV curing, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, electrodeless discharge lamps, LEDs, etc., which emit light in the 150 to 450 nm wavelength range, are used, with an output of 30 to 3,000 mJ / cm. 2 It is enough to irradiate it to some extent. After the ultraviolet irradiation, heating may be carried out as necessary to ensure complete curing.

[0089] The thickness of the cured coating film is usually 1 to 300 μm, preferably 2 to 250 μm, and more preferably 5 to 200 μm, in consideration of light transmission so that the photopolymerization initiator (C) can react uniformly.

[0090] In the present invention, the glass transition temperature (Tg) of the cured product (adhesive) of the adhesive composition is preferably −30° C. or higher, more preferably −30 to 50° C., even more preferably −20 to 45° C., particularly preferably −10 to 40° C., and especially preferably 0 to 30° C. If the glass transition temperature (Tg) is outside the above range, the adhesive strength tends to decrease when used as an adhesive.

[0091] The glass transition temperature (Tg) was measured as follows. That is, the adhesive composition was applied to an adhesive-friendly polyethylene terephthalate (PET) film (thickness: 125 μm) using an applicator so that the film thickness after curing would be 100 μm, and the applied adhesive composition was then irradiated with a tabletop UV irradiation device (manufactured by Eye Graphics, "Conveyor-type tabletop irradiation device") at 80 W / cm (high-pressure mercury lamp) × 18 cmH × 1.9 m / min × 3 Passes (cumulative irradiation dose: 2400 mJ / cm 2) and cured under the conditions described above, a test piece measuring 20 mm in length and 3 mm in width was cut out from the adhesive sheet for adhesive strength measurement. Using this test piece, measurements were carried out using the tensile mode of a dynamic viscoelasticity measuring device "DVA-225" manufactured by IT Measurement Control Co., Ltd., at a frequency of 1 Hz, a heating rate of 3°C / min, and a strain of 0.1%, and the ratio (tanδ) of the imaginary part (loss modulus) to the real part (storage modulus) of the obtained complex modulus was determined, and the maximum peak temperature of this tanδ was taken as the glass transition temperature (°C).

[0092] The gel fraction of the pressure-sensitive adhesive composition after curing is preferably 10% by weight or more, more preferably 20 to 95% by weight, even more preferably 30 to 90% by weight, and particularly preferably 40 to 85% by weight, from the viewpoints of durability and adhesive strength. If the gel fraction is too low, the cohesive strength tends to decrease, resulting in a decrease in durability. However, if the gel fraction is too high, the cohesive strength tends to increase, resulting in a decrease in adhesive strength.

[0093] The gel fraction is a measure of the degree of crosslinking and is calculated, for example, by the following method. A cured coating sheet (without a separator) consisting of a cured coating formed on a polymer sheet (e.g., a PET film) serving as a substrate is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours. The gel fraction is calculated as the weight percentage of the insoluble cured coating components remaining in the wire netting after immersion relative to the weight of the cured coating components before immersion, excluding the weight of the substrate.

[0094] In the present invention, the active energy ray-curable resin composition containing the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated group monomer (B) has low viscosity and further has good adhesion to various members, particularly good adhesive strength when used as an adhesive. Therefore, the active energy ray-curable resin composition of the present invention can be applied to various applications such as coating agents, paints, inks, adhesives, etc., and is particularly useful as an adhesive because of its good adhesive strength. [Example]

[0095] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight. The number average molecular weight, weight average molecular weight and gel fraction of the urethane (meth)acrylate compound were measured according to the above-mentioned methods, and the bio content was calculated according to the above-mentioned methods.

[0096] The monofunctional urethane (meth)acrylate compound (A) was prepared as follows. [Urethane (meth)acrylate compound (A-1)] A four-neck flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet was charged with 11.08 parts of isophorone diisocyanate (a2), 83.23 parts of "Priplast 3199" as a polyester polyol (a1), 0.06 parts of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.01 parts of dibutyltin dilaurate as a reaction catalyst, and the mixture was reacted at 60 ° C. Next, 3.73 parts of 4-hydroxybutyl acrylate (a3) ​​and 1.96 parts of isohexadecanol (a4) were added to the system, and the reaction was terminated when the residual isocyanate group reached 0.3 wt % or less, yielding a composition containing a urethane (meth)acrylate compound (A-1).

[0097] [Urethane (meth)acrylate compound (A-2)] A four-neck flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet was charged with 11.24 parts of isophorone diisocyanate (a2), 84.44 parts of "Priplast 3199" as polyester polyol (a1), 0.06 parts of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.01 parts of dibutyltin dilaurate as a reaction catalyst, and the mixture was reacted at 60 ° C. Next, 3.78 parts of 4-hydroxybutyl acrylate (a3) ​​and 0.53 parts of 2-propanol (a4) were added to the system, and the reaction was terminated when the residual isocyanate group reached 0.3 wt % or less, yielding a composition containing a urethane (meth)acrylate compound (A-2).

[0098] Also, a bifunctional urethane (meth)acrylate compound (A') was prepared as follows. [Urethane (meth)acrylate compound (A'-1)] A four-neck flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet was charged with 11.51 parts of isophorone diisocyanate (a2), 86.44 parts of "Priplast 3199" as polyester polyol (a1), 0.06 parts of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.01 parts of dibutyltin dilaurate as a reaction catalyst, and the mixture was reacted at 60°C. Next, 2.05 parts of 4-hydroxybutyl acrylate (a3) ​​was charged to this system, and the reaction was terminated when the residual isocyanate group reached 0.3 wt% or less, yielding a composition containing a urethane (meth)acrylate compound (A'-1).

[0099] The following monofunctional ethylenically unsaturated monomers (B) were prepared. (B1-1): Isobornyl acrylate (Tg = 97°C) (Osaka Organic Chemical Industry Co., Ltd.) (B1-2): Cyclic trimethylolpropane formal acrylate (Tg = 27°C) (Osaka Organic Chemical Industry Co., Ltd.) (B1'-1): Acryloylmorpholine (Tg = 145°C) (KJ Chemicals) (B2-1): Tetrahydrofurfuryl acrylate (Tg = -15°C) (Tomoe Engineering Co., Ltd.) (B2-2): Phenoxyethyl acrylate (Tg = -22°C) (Kyoeisha Chemical Co., Ltd.) (B2-3): n-butyl acrylate (Tg = -50°C)

[0100] <Examples 1 to 8 and Comparative Examples 1 to 3> [Preparation of active energy ray-curable resin composition] A urethane (meth)acrylate compound and a monofunctional ethylenically unsaturated monomer were blended to obtain the composition shown in Table 1, and further, 4 parts of Omnirad 184 (manufactured by IGM Resin) was blended as a photopolymerization initiator relative to a total of 100 parts of the urethane (meth)acrylate compound and the monofunctional ethylenically unsaturated monomer to obtain an active energy ray-curable resin composition. The obtained active energy ray-curable resin compositions were evaluated as follows.

[0101] 〔viscosity〕 The viscosity of the obtained active energy ray-curable resin composition was measured at 60°C using an E-type viscometer and evaluated according to the following criteria. (Evaluation criteria) ◎ Less than 1500 mPa s ○ 1500 or more and less than 2500 mPa·s △ 2500 or more and less than 3500 mPa·s ×...3500mPa·s or more

[0102] [Adhesive strength] (Preparation of adhesive sheet (without lamination) for measuring adhesive strength) The obtained active energy ray-curable resin composition was applied to an easily adhesive treated polyethylene terephthalate (PET) film (thickness: 125 μm) using an applicator so that the film thickness after curing would be 100 μm. The UV irradiation surface was exposed to air and then irradiated with a tabletop UV irradiation device (manufactured by Eye Graphics, "Conveyor-type tabletop irradiation device") at 80 W / cm (high-pressure mercury lamp) × 18 cmH × 1.9 m / min × 3 Passes (cumulative irradiation dose: 2400 mJ / cm 2 ) and cured to obtain a pressure-sensitive adhesive sheet for measuring adhesive strength.

[0103] (Test Method) The resulting adhesive sheet for adhesive strength measurement was cut into a 25 mm x 100 mm piece and then pressed onto a stainless steel plate (SUS304BA plate) as an adherend by rolling it back and forth twice using a 2 kg rubber roller in an atmosphere of 23°C and 50% relative humidity to prepare a test specimen. This test specimen was left to stand in the same atmosphere for 30 minutes, and then subjected to a 180-degree peel test at a peel speed of 0.3 m / min to measure the adhesive strength (N / 25 mm) and evaluate it according to the following criteria. (Evaluation criteria) 〇...20N / 25mm or more △ 10N / 25mm or more and less than 20N / 25mm × Less than 10N / 25mm

[0104] (Preparation of adhesive sheet (laminated) for measuring adhesive strength) The obtained active energy ray-curable resin composition was applied to an easy-adhesion treated polyethylene terephthalate (PET) film (thickness: 125 μm) using an applicator so that the film thickness after curing would be 100 μm, and the film was then attached to a release film (thickness: 38 μm). The UV irradiation surface was not exposed to air and was exposed to a tabletop UV irradiation device (Eye Graphics, "Conveyor-type tabletop irradiation device") using a 80W / cm (high-pressure mercury lamp) x 18cmH x 1.9m / min x 3 passes (cumulative irradiation dose 2400mJ / cm 2 ) and cured to obtain a pressure-sensitive adhesive sheet for measuring adhesive strength.

[0105] (Test Method) The resulting adhesive sheet for adhesive strength measurement was cut into a piece of 25 mm x 100 mm, the release film was peeled off, and the piece was pressed against a stainless steel plate (SUS304BA plate) as an adherend by rolling it back and forth twice using a 2 kg rubber roller in an atmosphere of 23°C and 50% relative humidity to prepare a test piece. After leaving this test piece in the same atmosphere for 30 minutes, a 180-degree peel test was performed at a peel speed of 0.3 m / min, and the adhesive strength (N / 25 mm) was measured and evaluated according to the following criteria. (Evaluation criteria) 〇...20N / 25mm or more △ 10N / 25mm or more and less than 20N / 25mm × Less than 10N / 25mm

[0106] [Table 1]

[0107] From the results in Table 1 above, the active energy ray-curable resin compositions of Examples 1 to 8 contained a monofunctional urethane (meth)acrylate, an ethylenically unsaturated monomer having a high glass transition temperature within a predetermined range, and an ethylenically unsaturated monomer having a low glass transition temperature within a predetermined range, and therefore had low viscosity and good adhesive strength. Furthermore, the active energy ray-curable resin compositions of Examples 1 to 8 used a plant-derived polyol as a raw material for the monofunctional urethane (meth)acrylate compound (A), and therefore were able to increase the bio-content and reduce the environmental impact. In contrast, the active energy ray-curable resin compositions of Comparative Examples 1 and 2 used two types of monofunctional ethylenically unsaturated monomers with high glass transition temperatures in combination, and did not use a monofunctional ethylenically unsaturated monomer with low glass transition temperatures, so they had high viscosity and some also had poor adhesive strength, and were unable to achieve both low viscosity and adhesive strength. The active energy ray-curable resin composition of Comparative Example 3 used a bifunctional urethane (meth)acrylate, so the viscosity was high and the object of the present invention was not satisfied. From the above, it is clear that it is important to contain a monofunctional urethane (meth)acrylate and two monofunctional ethylenically unsaturated monomers having glass transition temperatures within a predetermined range. [Industrial Applicability]

[0108] The active energy ray-curable resin composition of the present invention has low viscosity and exhibits good adhesion to various members, particularly good adhesive strength when used as a pressure-sensitive adhesive, and can be used in a variety of applications such as coating agents, paints, inks, and pressure-sensitive adhesives.

Claims

1. Contains a monofunctional urethane (meth)acrylate compound (A) and a monofunctional ethylenically unsaturated monomer (B), the monofunctional urethane (meth)acrylate compound (A) is a reaction product of a polyol (a1), a polyisocyanate (a2), a hydroxyl group-containing (meth)acrylate (a3), and a monool (a4); the polyol (a1) is at least one selected from the group consisting of polyester-based polyols, polyether-based polyols, polycarbonate-based polyols, and polysiloxane-based polyols; the monofunctional ethylenically unsaturated monomer (B) contains a monofunctional ethylenically unsaturated monomer (B1) having a glass transition temperature of 0°C or higher and 130°C or lower when made into a homopolymer, and a monofunctional ethylenically unsaturated monomer (B2) having a glass transition temperature of -60°C or higher and lower than 0°C when made into a homopolymer, the monofunctional ethylenically unsaturated monomer (B2) having a glass transition temperature of −60° C. or higher and lower than 0° C. when made into a homopolymer is at least one selected from the group consisting of alkyl (meth)acrylates, aromatic (meth)acrylates, heterocyclic (meth)acrylates, and alkoxy group-containing (meth)acrylates; the content of the monofunctional ethylenically unsaturated monomer (B) is 20 to 100 parts by weight based on 100 parts by weight of the monofunctional urethane (meth)acrylate compound (A); the content ratio (B1 / B2) of the monofunctional ethylenically unsaturated monomer (B1) that, when made into a homopolymer, gives a glass transition temperature of 0°C or more and 130°C or less, and the content ratio (B2) of the monofunctional ethylenically unsaturated monomer (B2) that, when made into a homopolymer, gives a glass transition temperature of -60°C or more and less than 0°C, is 70 / 30 to 30 / 70 (weight ratio).

2. 2. The active energy ray-curable resin composition according to claim 1, wherein the polyol (a1) is a plant-derived polyol.

3. 3. The active energy ray-curable resin composition according to claim 1, wherein the monool (a4) is a monool having 3 or more carbon atoms.

4. The active energy ray-curable resin composition according to any one of claims 1 to 3, characterized in that the monofunctional urethane (meth)acrylate compound (A) is a monofunctional urethane (meth)acrylate compound in which an isocyanate group in a compound (X) containing isocyanate groups at both ends, which is a reaction product of a polyol (a1) and a polyvalent isocyanate (a2), and a hydroxyl group possessed by the hydroxyl group-containing (meth)acrylate (a3) ​​and the monool (a4), respectively, form a urethane bond.

5. 5. The active energy ray-curable resin composition according to claim 1, wherein the monofunctional urethane (meth)acrylate compound (A) has a weight average molecular weight of 5,000 to 100,000.

6. The active energy ray-curable resin composition according to any one of claims 1 to 5, characterized in that the composition comprising the monofunctional urethane (meth)acrylate compound (A) and the monofunctional ethylenically unsaturated monomer (B) has a bio-degree of 50 C% or more.

7. The active energy ray-curable resin composition according to any one of claims 1 to 6, further comprising a photopolymerization initiator (C).

8. A pressure-sensitive adhesive composition comprising the active energy ray-curable resin composition according to any one of claims 1 to 7.

9. A pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to claim 8.

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